Focal cryotherapy for clinically unilateral, low-intermediate risk prostate cancer in 73 men with a median follow-up of 3.7 years

Which technology to select for primary focal treatment of prostate cancer?-European Section of Urotechnology (ESUT) position statement

BACKGROUND

With growing interest in focal therapy (FT) of prostate cancer (PCa) there is an increasing armamentarium of treatment modalities including high-intensity focused ultrasound (HIFU), cryotherapy, focal laser ablation (FLA), irreversible electroporation (IRE), vascular targeted photodynamic therapy (VTP), focal brachytherapy (FBT) and stereotactic ablative radiotherapy (SABR). Currently there are no clear recommendations as to which of these technologies are appropriate for individual patient characteristics. Our intention was to review the literature for special aspects of the different technologies that might be of advantage depending on individual patient and tumour characteristics.

METHODS

The current literature on FT was screened for the following factors: morbidity, repeatability, tumour risk category, tumour location, tumour size and prostate volume and anatomical issues. The ESUT expert panel arrived at consensus regarding a position statement on a structured pathway for available FT technologies based on a combination of the literature and expert opinion.

RESULTS

Side effects were low across different studies and FT modalities with urinary continence rates of 90-100% and erectile dysfunction between 5 and 52%. Short to medium cancer control based on post-treatment biopsies were variable between ablative modalities. Expert consensus suggested that posterior lesions are better amenable to FT using HIFU. Cryotherapy provides best possible outcomes for anterior tumours. Apical lesions, when treated with FBT, may yield the least urethral morbidity.

CONCLUSIONS

Further prospective trials are required to assess medium to long term disease control of different ablative modalities for FT. Amongst different available FT modalities our ESUT expert consensus suggests that some may be better for diffe`rent tumour locations. Tumour risk, tumour size, tumour location, and prostate volume are all important factors to consider and might aid in designing future FT trials.

Medium-term Follow-up of Vascular-targeted Photodynamic Therapy of Localized Prostate Cancer Using TOOKAD Soluble WST-11 (Phase II Trials)

BACKGROUND AND OBJECTIVE

To assess the medium-term tumor control in patients with localized prostate cancer (PCa) treated with vascular-targeted photodynamic (VTP) therapy with TOOKAD Soluble WST11 (VTP) and to assess the medium-term tolerability of the treatment.

DESIGN, SETTING, PARTICIPANTS, AND INTERVENTION

During the clinical phase II studies, 68 patients were treated with VTP under optimal treatment conditions (WST11 at 4mg/kg, light energy at 200J/cm, and a light density index ≥1) and have been included in a 3.5-yr follow-up.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Post-interventional visits were scheduled every 6 mo and conducted as per local standard practice in each study center. Cancer-free status was assessed by means of prostate-specific antigen kinetics, multiparametric magnetic resonance imaging and/or prostate biopsies.

RESULTS AND LIMITATIONS

At the end of the 3.5-yr follow-up, overall successful focal ablation was achieved for 51 patients (75%). Cancer was identified in the untreated lobe in 17 patients (25%). In total, 34 patients (50%) were cancer-free in both the prostate lobes. In case of recurrent/persistent malignancy, the Gleason score remained consistent or changed at the maximum by one point (upgrading by 1 Gleason point to 3+4 for eight patients and 4+3 for two patients). There were 64 related adverse events (AEs): 48% were Clavien grade I, 47% were grade II, and 5% were grade III. There were no Clavien grade IV and V AEs. Limitations included small sample size and heterogeneity in the follow-up for some centers.

CONCLUSIONS

VTP is a safe and efficient treatment and represents an alternative option for localized low-risk PCa management over the medium term. Precise diagnostic methods and imaging tools are thereby essential requirements to ensure safe and complete targeted therapy.

PATIENT SUMMARY

In this report, we looked at the medium-term outcomes of focal photodynamic therapy for early-stage prostate cancer. We found that this form of treatment is efficient and might have the potential to become a therapeutic option for low-risk cancer. Effectiveness depends on precise diagnostic methods, such as magnetic resonance imaging and accurate biopsy.

"Super-active surveillance": MRI ultrasound fusion biopsy and ablation for less invasive management of prostate cancer

Multiparametric magnetic resonance imaging (mpMRI) of the prostate has allowed clinicians to better visualize and target suspicious lesions during biopsy. Targeted prostate biopsies give a more accurate representation of the true cancer volume and stage so that appropriate treatment or active surveillance can be selected. Advances in technology have led to the development of MRI and ultrasound fusion platforms used for targeted biopsies, monitoring cancer progression, and more recently for the application of focal therapy. Lesions visualized on mpMRI can be targeted for ablation with a variety of energy sources employed under both local and general anesthesia. Focal ablation may offer an alternative option for treating prostate cancer as compared to the well-established interventions of whole-gland radiation or prostatectomy. Focal ablation may also be an option for patients on active surveillance who wish to be even more "active" in their surveillance. In this review, we describe the advancements and development of fusion biopsies, the rationale behind focal therapy, and introduce focal ablative techniques for indolent prostate cancers ("super-active surveillance"), including cryoablation and focal laser ablation (FLA) and the subsequent MRI/biopsy surveillance.

MR-guided biopsy and focal therapy: new options for prostate cancer management

PURPOSE OF REVIEW

Options for prostate cancer management are rapidly expanding. The recent advent of MRI technology has led to guided prostate biopsies by radiologists working in-bore or by urologists using MR/US fusion technology. The resulting tumor visualization now provides the option of focal therapy. Currently available are highly directed energies - focused ultrasound (HIFU), cryotherapy, and laser - all offering the hope of curing prostate cancer with few side effects.

RECENT FINDINGS

MRI now enables visualization of many prostate cancers. MR/US fusion biopsy makes possible the targeted biopsy of suspicious lesions efficiently in the urology clinic. Several fusion devices are now commercially available. Focal therapy, a derivative of targeted biopsy, is reshaping the approach to treatment of some prostate cancers. Focal laser ablation, originally done in the MRI gantry (in-bore), promises to soon become feasible in a clinic setting (out-of-bore) under local anesthesia. Other focal therapy options, including HIFU and cryotherapy, are currently available. Herein are summarized outcomes data on focal therapy modalities.

SUMMARY

MRI-guided biopsy is optimizing prostate cancer diagnosis. Focal therapy, an outgrowth of guided biopsy, promises to become a well tolerated and effective approach to treating many men with prostate cancer while minimizing the risks of incontinence and impotence from radical treatment.

Effects of Focal vs Total Cryotherapy and Minimum Tumor Temperature on Patient-reported Quality of Life Compared With Active Surveillance in Patients With Prostate Cancer

OBJECTIVE

To investigate the effects of focal (hemiablation) or total cryotherapy and minimum tumor temperature on patient-reported quality of life (QoL) in patients with prostate cancer.

METHODS

An Institutional Review Board-approved database was reviewed for patients who underwent cryotherapy or active surveillance (AS). QoL questionnaire responses were collected and scores were analyzed for differences between focal and total cryotherapy and between very cold (<-76°C) and moderate-cold (≥-76°C) minimum tumor temperatures.

RESULTS

A total of 197 patients responded to a total of 547 questionnaires. Focal and total cryotherapy patients had initially lower sexual function scores relative to AS (year 1 mean difference focal: -31.7, P <.001; total: -48.1, P <.001). Focal cryotherapy was associated with a more rapid improvement in sexual function. Both focal and total cryotherapy sexual function scores were not statistically significantly different from the AS cohort by postprocedural year 4. Very cold and moderate-cold temperatures led to initially lower sexual function scores relative to AS (year 1 very cold: -38.1, P <.001; moderate-cold: -30.7, P <.001). Moderate-cold temperature scores improved more rapidly than those of very cold temperature. Neither very cold nor moderate-cold temperatures had a statistically significant difference in sexual function scores relative to AS by postprocedural year 4. Urinary function and bowel habits were not significantly different between focal and total cryotherapy and between very cold and moderate-cold temperature groups.

CONCLUSION

Focal cryotherapy and moderate-cold (≥-76°C) temperature were associated with favorable sexual function relative to total cryotherapy and very cold temperature, respectively. No significant differences in urinary function or bowel habits were observed between groups.

PSA kinetics following primary focal cryotherapy (hemiablation) in organ-confined prostate cancer patients

PURPOSE

We aim to evaluate prostate-specific antigen (PSA) trends in post-primary focal cryotherapy (PFC) patients.

MATERIALS AND METHODS

This was an institutional review board-approved retrospective study of PFC patients from 2010 to 2015. Patients with at least one post-PFC PSA were included in the study. Biochemical recurrence (BCR) was determined using the Phoenix criteria. PSA bounce was also assessed. We analyzed rates of change of PSA over time of post-PFC between BCR and no BCR groups. PSA-derived variables were analyzed as potential predictors of BCR.

RESULTS

A total of 104 PFC patients were included in our analysis. Median (range) age and follow-up time were 66 (48-82) years and 19 (6.3-38.6) months, respectively. Four (3.8%) patients experienced PSA bounce. The median percent drop in first post-PFC PSA of 80.0% was not associated with BCR (p = 0.256) and may indicate elimination of the index lesion. The rate of increase of PSA in BCR patients was significantly higher compared to patients who did not recur (median PSA velocity (PSAV): 0.15 vs 0.04 ng/ml/month, p = 0.001). Similar to PSAV (HR 9.570, 95% CI 3.725-24.592, p < 0.0001), PSA nadir ≥ 2 ng/ml [HR (hazard ratio) 1.251, 95% CI 1.100-1.422, p = 0.001] was independently associated with BCR.

CONCLUSION

A significant drop in post-PFC PSA may indicate elimination of the index lesion. Patients who are likely to recur biochemically have a significantly higher PSAV compared to those who do not recur. Nadir PSA of less than 2 ng/ml may be considered the new normal PSA in focal cryotherapy (hemiablation) follow-up.

Focal Ablation of Early-Stage Prostate Cancer: Candidate Selection, Treatment Guidance, and Assessment of Outcome

Prostate cancer lesions smaller than 0.5 m³, or Gleason pattern 3, are likely clinically insignificant. Clinically significant disease is often limited to a single index lesion. Focal ablation targets this index lesion, maintains oncological control, and minimizes complications by preserving healthy prostate tissue. Template mapping biopsy or multiparametric MRI-targeted biopsies are used to identify appropriate index lesions. Multiple energy modalities have been tested, including high-intensity frequency ultrasound, cryoablation, laser ablation, photodynamic therapy, focal brachytherapy, radiofrequency ablation, irreversible electroporation. Outcome is assessed by biopsy of the target area, triggered by prostate-specific antigen measurements or MRI imaging, or performed per protocol at 12 months.

[Focal therapy of prostate cancer]

The target of focal therapy (FT) in prostate cancer (PC) is partial treatment of the prostate aiming at preserving surrounding anatomical structures. The intention is to minimize typical side effects of radical treatment options combined with local tumor control. Numerous established and new technologies are used. Results of published studies showed a good safety profile, few side effects and good preservation of functional results. Oncologic long-term data are lacking so far. Photodynamic therapy (PDT) is the only technology that has been studied in a published prospective randomized trial. The FT is challenged by the multifocality of PC; therefore, the quality of prostate biopsy, histopathological assessment as well as imaging are of paramount importance. Multiparametric magnetic resonance imaging (MRI) has gained increasing importance. The FT is experimental and should only be offered within clinical trials.

Low-risk Prostate Cancer: Identification, Management, and Outcomes

CONTEXT

The incidence of low-risk prostate cancer (PCa) has increased as a consequence of prostate-specific antigen testing.

OBJECTIVE

In this collaborative review article, we examine recent literature regarding low-risk PCa and the available prognostic and therapeutic options.

EVIDENCE ACQUISITION

We performed a literature review of the Medline, Embase, and Web of Science databases. The search strategy included the terms: prostate cancer, low risk, active surveillance, focal therapy, radical prostatectomy, watchful waiting, biomarker, magnetic resonance imaging, alone or in combination.

EVIDENCE SYNTHESIS

Prospective randomized trials have failed to show an impact of radical treatments on cancer-specific survival in low-risk PCa patients. Several series have reported the risk of adverse pathologic outcomes at radical prostatectomy. However, it is not clear if these patients are at higher risk of death from PCa. Long-term follow-up indicates the feasibility of active surveillance in low-risk PCa patients, although approximately 30% of men starting active surveillance undergo treatment within 5 yr. Considering focal therapies, robust data investigating its impact on long-term survival outcomes are still required and therefore should be considered experimental. Magnetic resonance imaging and tissue biomarkers may help to predict clinically significant PCa in men initially diagnosed with low-risk disease.

CONCLUSIONS

The incidence of low-risk PCa has increased in recent years. Only a small proportion of men with low-risk PCa progress to clinical symptoms, metastases, or death and prospective trials have not shown a benefit for immediate radical treatments. Tissue biomarkers, magnetic resonance imaging, and ongoing surveillance may help to identify those men with low-risk PCa who harbor more clinically significant disease.

PATIENT SUMMARY

Low-risk prostate cancer is very common. Active surveillance has excellent long-term results, while randomized trials have failed to show a beneficial impact of immediate radical treatments on survival. Biomarkers and magnetic resonance imaging may help to identify which men may benefit from early treatment.

Multimodal Imaging in Focal Therapy Planning and Assessment in Primary Prostate Cancer

PURPOSE

There is increasing interest in focal therapy (male lumpectomy) of localized low-intermediate risk prostate cancer. Focal therapy is typically associated with low morbidity and provides the possibility of retreatment. Imaging is pivotal in stratification of men with localized prostate cancer for active surveillance, focal therapy or radical intervention. This article provides a concise review of focal therapy and the evolving role of imaging in this clinical setting.

METHODS

We performed a narrative and critical literature review by searching PubMed/Medline database from January 1997 to January 2017 for articles in the English language and the use of search keywords "focal therapy", "prostate cancer", and "imaging".

RESULTS

Most imaging studies are based on multiparametric magnetic resonance imaging. Transrectal ultrasound is inadequate independently but multiparametric ultrasound may provide new prospects. Positron emission tomography with radiotracers targeted to various underlying tumor biological features may provide unprecedented new opportunities. Multimodal Imaging appears most useful in localization of intraprostatic dominant index lesions amenable to focal therapy, in early assessment of therapeutic efficacy and potential need for additional focal treatments or transition to whole-gland therapy, and in predicting short-term and long-term outcomes.

CONCLUSION

Multimodal imaging is anticipated to play an increasing role in the focal therapy planning and assessment of low-intermediate risk prostate cancer and thereby moving this form of treatment option forward in the clinic.

New advances in focal therapy for early stage prostate cancer

INTRODUCTION

Prostate focal therapy offers men the opportunity to achieve oncological control while preserving sexual and urinary function. The prerequisites for successful focal therapy are to accurately identify, localize and completely ablate the clinically significant cancer(s) within the prostate. We aim to evaluate the evidence for current and upcoming technologies that could shape the future of prostate cancer focal therapy in the next five years. Areas covered: Current literature on advances in patient selection using imaging, biopsy and biomarkers, ablation techniques and adjuvant treatments for focal therapy are summarized. A literature search of major databases was performed using the search terms 'focal therapy', 'focal ablation', 'partial ablation', 'targeted ablation', 'image guided therapy' and 'prostate cancer'. Expert commentary: Advanced radiological tools such as multiparametric magnetic resonance imaging (mpMRI), multiparametric ultrasound (mpUS), prostate-specific-membrane-antigen positron emission tomography (PSMA-PET) represent a revolution in the ability to understand cancer function and biology. Advances in ablative technologies now provide a menu of modalities that can be rationalized based on lesion location, size and perhaps in the near future, pre-determined resistance to therapy. However, these need to be carefully studied to establish their safety and efficacy parameters. Adjuvant strategies to enhance focal ablation are under development.

Assessment of Cryosurgical Device Performance Using a 3D Tissue-Engineered Cancer Model

As the clinical use of cryoablation for the treatment of cancer has increased, so too has the need for knowledge on the dynamic environment within the frozen mass created by a cryoprobe. While a number of factors exist, an understanding of the iceball size, critical isotherm distribution/penetration, and the resultant lethal zone created by a cryoprobe are critical for clinical application. To this end, cryoprobe performance is typically characterized based on the iceball size and temperature penetration in phantom gel models. Although informative, these models do not provide information as to the impact of heat input from surrounding tissue nor give any information on the ablative zone created. As such, we evaluated the use of a tissue-engineered tumor model (TEM) to assess cryoprobe performance including iceball size, real-time thermal profile distribution, and resultant ablative zone. Studies were conducted using an Endocare V-probe cryoprobe, with a 10/5/10 double freeze–thaw protocol using prostate and renal cancer TEMs. The data demonstrate the generation of a 33- to 38-cm3 frozen mass with the V-Probe cryoprobe following the double freeze of which ∼12.7 and 6.5 cm3 was at or below −20°C and −40°C, respectively. Analysis of ablation zone using fluorescence microscopy 24 hours postthaw demonstrated that the internal ∼40% of the frozen mass was completely ablated, whereas in the periphery of the iceball (outer 1 cm region), a gradient of partial to minimal destruction was observed. These findings correlated well with clinical reports on renal and prostate cancer cryoablation. Overall, this study demonstrates that TEMs provide an effective model for a more complete characterization of cryoablation device performance. The data demonstrate that while the overall iceball size generated in the TEM was consistent with published reports from phantom models, the integration of an external heat load, circulation, and cellular components more closely reflect an in vivo setting and the impact of penetration of the critical (−20°C and −40°C) isotherms into the tissue. This is important as it is well appreciated in clinical practice that the heat load of a tissue, cryoprobe proximity to vasculature, and so on, can impact outcome. The TEM model provides a means of characterizing the impact on ablative dose delivery allowing for a better understanding of probe performance and potential impact on ablative outcome.

Magnetically-actuated drug delivery device (MADDD) for minimally invasive treatment of prostate cancer: An in vivo animal pilot study

BACKGROUND

The vast majority of prostate cancer presents clinically localized to the prostate without evidence of metastasis. Currently, there are several modalities available to treat this particular disease. Despite radical prostatectomy demonstrating a modest prostate cancer specific mortality benefit in the PIVOT trial, several novel modalities have emerged to treat localized prostate cancer in patients that are either not eligible for surgery or that prefer an alternative approach.

METHODS

Athymic nude mice were subcutaneously inoculated with prostate cancer cells. The mice were divided into four cohorts, one cohort untreated, two cohorts received docetaxel (10 mg/kg) either subcutaneously (SC) or intravenously (IV) and the fourth cohort was treated using the magnetically-actuated docetaxel delivery device (MADDD), dispensing 1.5 μg of docetaxel per 30 min treatment session. Treatment in all three therapeutic arms (SC, IV, and MADDD) was administered once weekly for 6 weeks. Treatment efficacy was measured once a week according to tumor volume using ultrasound. In addition, calipers were used to assess tumor volume.

RESULTS

Animals implanted with the device demonstrated no signs of distress or discomfort, neither local nor systemic symptoms of inflammation and infection. Using an independent sample t-test, the tumor growth rate of the treated tumors was significant when compared to the control. Post hoc Tukey HSD test results showed that the mean tumor growth rate of our device cohort was significantly lower than SC and control cohorts. Moreover, IV cohort showed slight reduction in mean tumor growth rates than the ones from the device cohort, however, there was no statistical significance in tumor growth rate between these two cohorts. Furthermore, immunohistochemistry demonstrated an increased cellular apoptosis in the MADDD treated tumors and a decreased proliferation when compared to the other cohorts. In addition, IV cohort showed increased treatment side effects (weight loss) when compared to the device cohort. Finally, MADDD showed minimal expression of CD45 comparable to the control cohort, suggesting no signs of chronic inflammation.

CONCLUSIONS

In conclusion, this study showed for the first time that MADDD, clearly suppressed tumor growth in local prostate cancer tumors. This could potentially be a novel clinical treatment approach for localized prostate cancer.

Salvage high-intensity focused ultrasound (HIFU) for locally recurrent prostate cancer after failed radiation therapy: Multi-institutional analysis of 418 patients

OBJECTIVE

To report the oncological outcome of salvage high-intensity focused ultrasound (S-HIFU) for locally recurrent prostate cancer after external beam radiotherapy (EBRT) from a multicentre database.

PATIENTS AND METHODS

This retrospective study comprises patients from nine centres with local recurrent disease after EBRT treated with S-HIFU from 1995 to 2009. The biochemical failure-free survival (bFFS) rate was based on the 'Phoenix' definition (PSA nadir + 2 ng/mL). Secondary endpoints included progression to metastasis and cancer-specific death. Kaplan-Meier analysis was performed examining overall (OS), cancer-specific (CSS) and metastasis-free survival (MFS). Adverse events and quality of life status are reported.

RESULTS

In all, 418 patients with a mean (SD) follow-up of 3.5 (2.5) years were included. The mean (SD) age was 68.6 (5.8) years and the PSA level before S-HIFU was 6.8 (7.8) ng/mL. The median PSA nadir after S-HIFU was 0.19 ng/mL. The OS, CSS and MFS rates at 7 years were 72%, 82% and 81%, respectively. At 5 years the bFFS rate was 58%, 51% and 36% for pre-EBRT low-, intermediate- and high-risk patients, respectively. The 5-year bFFS rate was 67%, 42% and 22% for pre-S-HIFU PSA level ≤4, 4-10 and ≥10 ng/mL, respectively. Complication rates decreased after the introduction of specific post-RT parameters: incontinence (grade II or III) from 32% to 19% (P = 0.002); bladder outlet obstruction or stenosis from 30% to 15% (P = 0.003); recto-urethral fistula decreased from 9% to 0.6% (P < 0.001). Study limitations include being a retrospective analysis from a registry with no control group.

CONCLUSION

S-HIFU for locally recurrent prostate cancer after failed EBRT is associated with 7-year CSS and MFS rates of >80% at a price of significant morbidity. S-HIFU should be initiated early following EBRT failure.

Robotic System for MRI-guided Focal Laser Ablation in the Prostate

MRI-conditional robotic platforms have proved to be an effective approach for image guided interventions. In this study, a computer-assisted, pneumatically-actuated robot was designed, built, and tested for MRI-guided prostate cancer focal laser ablation (FLA). The robotic manipulator provides two active planar degrees of freedom (DoFs) by using a customized CoreXY frame, and one passive rotational DoF. A remote insertion mechanism improves the surgical workflow by keeping the patients inside the scanner during needle insertion. The robotic manipulator was tested in a 3T MR scanner to evaluate its MR compliance, and the results demonstrated that the signal-to-noise ratio (SNR) variation was less than 8%. The in-scanner template positioning accuracy test demonstrated that the manipulator achieves high targeting accuracy with a mean error of 0.46 mm and a standard deviation of 0.25mm. Phantom studies have shown that the needle insertion accuracy of the manipulator is within 2mm (Mean = 1.7mm, StD = 0.2mm).

Results of multiparametric transrectal ultrasound-based focal high-dose-rate dose escalation combined with supplementary external beam irradiation in intermediate- and high-risk localized prostate cancer patients

PURPOSE

Clinical results of a biologic information-based focused dose escalation combined with dose de-escalation for the whole organ in external beam radiotherapy + high-dose-rate brachytherapy (HDR-BT) boost application for localized prostate cancer in a consecutively treated patient cohort.

METHODS AND MATERIALS

One hundred thirty patients were treated with external beam radiotherapy (50 Gy) complementary to two multiparametric transrectal ultrasound-guided 15 Gy HDR-BT fractions. Real-time multiparametric transrectal ultrasound-based biologic planning for high-dose-rate boost dose planning used the summation of gray scale and Doppler sonography imaging + biopsy information. Target subvolumes received HDR-BT dose escalation up to 60 Gy/fraction. Dose-volume histogram parameters, organ at risks doses, and toxicity results were investigated.

RESULTS

The median followup was 4.3 years, the median age was 68.62 years, and the mean initial prostate-specific antigen was 18.69 ng/mL. Low-, intermediate-, and high-risk constituted 69%, 21%, and 10% of the patients, respectively. The mean peripheral dose was 3.9 Gy per fraction. Prostate-specific antigen nadir was in 93% of the patients ≤1 ng/mL. Quality parameters were as follows: D₉₀: 6.58 Gy, V₁₀₀: 30.36%, V₁₅₀: 9.96%, V₂₀₀: 3.16%, uD_0.1: 7.34 Gy, uD₂: 9.34 Gy, rD₀₁: 10.56 Gy, and rD₂: 8.32 Gy, respectively. We observed G1, G2, G3 urinary toxicity in 17/130, 11/130, and 2/130 patients, respectively. Rectal toxicity: G1 and G2 occurred in 19/130 and 2/130 patients with mean dose values G1: 8.2 Gy and G2: 8.76 Gy. Analysis of variance test resulted in no correlation between toxicities and any other investigated factors.

CONCLUSIONS

Focused extreme dose escalation with low prostate mean peripheral dose results in excellent long-term outcome data and very high focal boost doses and is causing no enhancement in late treatment toxicity.

Magnetic resonance imaging-transrectal ultrasound fusion focal cryotherapy of the prostate: A prospective development study

OBJECTIVES

The use of software-based magnetic resonance-transrectal ultrasound fusion to deliver focal therapy may increase the precision of treatment. This is a prospective development study assessing the feasibility of Magnetic resonance imaging-transrectal ultrasound (MRI-TRUS) fusion focal cryotherapy.

METHODS AND MATERIALS

Consecutive patients undergoing focal cryotherapy were included in an academic registry (December 2013-June 2014). MRI-TRUS fusion focal cryotherapy was offered to men with visible clinically significant prostate cancer (Galil SeedNet system). Eligibility was determined by multiparametric MRI (mpMRI), and transperineal template mapping or targeted biopsies. A rigid fusion platform (Biojet) was used with the operator ensuring the ice ball covered at least the lesion. Adverse events were scored using the NCICTC V4. Genitourinary toxicity was assessed using patient-reported outcome measures (IPSS, IIEF-15, and UCLA-EPIC). Early contrast-enhanced MRI and mpMRI at 6 to 12 months were used to assess extent of lesion ablation.

RESULTS

Of 23 patients scheduled, 5 did not have image fusion owing to surgeon preference. Overall, 18 patients undergoing image-fusion cryotherapy had median age of 68 (interquartile range [IQR]: 65-73) years and median preoperative prostate-specific antigen = 9.54 (5.65-16)ng/ml. In all, 13 (72.2%) and 5 (27.8%) patients had intermediate and high-risk cancer, respectively. In total, 10 adverse events were reported with one of these as serious (grade 3) because of admission for hematuria requiring wash out only. There was no difference in the IIEF-15 between baseline and study end (P = 0.24). The IPSS remained stable (P = 0.12), whereas the UCLA-EPIC tended to improve (P = 0.065). The prostate-specific antigen level significantly decreased at 1.8 (1.04-2.93) ng/ml (P<0.001). Both early and late mpMRI showed no residual disease in the treated area. In 2 men, radiological progression of known contralateral disease was observed; both underwent focal high intensity focused ultrasound.

CONCLUSION

MRI-TRUS fusion focal cryotherapy is feasible in most patients and seems to accurately guide ablation demonstrated by posttreatment imaging. Additional studies are needed to determine efficacy using postcryotherapy biopsy.

Focal therapy in prostate cancer: A review of seven common controversies

Radical treatments such as prostatectomy and radiotherapy have demonstrated success in terms of biochemical and disease-specific survival for localised prostate cancer. However, whilst the end goal of any cancer treatment is to control or cure disease it must also do so by minimising any side effects that may be experienced by the patient. Focal therapy as a concept aims to redress this established therapeutic ratio by treating areas of the prostate affected by significant disease as opposed to treating the entire gland. However, there are a number of common criticisms of focal therapy - we deem the seven sins - that require further interrogation.

Focal therapy as primary treatment for localized prostate cancer: definition, needs and future

Focal therapy (FT) may offer a promising treatment option in the field of low to intermediate risk localized prostate cancer. The aim of this concept is to combine minimal morbidity with cancer control as well as maintain the possibility of retreatment. Recent advances in MRI and targeted biopsy has improved the diagnostic pathway of prostate cancer and increased the interest in FT. However, before implementation of FT in routine clinical practice, several challenges are still to overcome including patient selection, treatment planning, post-therapy monitoring and definition of oncologic outcome surrogates. In this article, relevant questions regarding the key steps of FT are critically discussed and the main available energy modalities are analyzed taking into account their advantages and unmet needs.

Outcomes and toxicities in patients treated with definitive focal therapy for primary prostate cancer: systematic review

AIM

This systematic review summarizes the clinical data on focal therapy (FT) when used alone as definitive therapy for primary prostate cancer (PCa).

METHODS

The protocol is detailed in the online PROSPERO database, registration No. CRD42014014765. Articles evaluating any form of FT alone as a definitive treatment for PCa in adult male patients were included.

RESULTS

Of 10,419 identified articles, 10,401 were excluded, and thus leaving 18 for analysis. In total, 2288 patients were treated using seven modalities. The outcomes of FT in PCa seem to be similar to those observed with whole gland therapy and with fewer side effects.

CONCLUSION

Further research, including prospective randomized trials, is warranted to elucidate the potential advantages of focal radiation techniques for treating PCa. Prospero Registration Number: CRD42014014765.

MRI-guided focal therapy of prostate cancer

With the advent of focal therapy as a recognized treatment option for men with prostate cancer, there are a host of emerging interventions that take advantage of MRI for image guidance. Focal therapy affords a middleground option for patients with low- to intermediate-grade prostate cancer by providing a means of keeping their cancer at bay while avoiding the negative consequences of radical therapies. However, the practice of focal treatment is far from straightforward, with some believing focal treatment errs on the side of overtreatment among patients with low-grade cancer; others worry it is undertreatment in potentially significant multifocal disease. Further research is necessary, both relating to focal therapy in general and to the utility of each MRI-guided focal treatment discussed.

Prostate-specific antigen vs. magnetic resonance imaging parameters for assessing oncological outcomes after high intensity-focused ultrasound focal therapy for localized prostate cancer

INTRODUCTION

Focal therapy for localized prostate cancer has the potential for oncological control without the side effects of radical therapies. However, there is currently no validated method for monitoring treatment success. We assessed the diagnostic performance of prostate-specific antigen (PSA) parameters and MRI compared to histological outcomes following focal therapy.

PATIENTS AND METHODS

Patients from 3 Ethics Review Board approved prospective studies of focal high intensity-focused ultrasound (HIFU) (Sonablate 500) for localized prostate cancer (T1c-T3a, Gleason grade≤4+3, and PSA≤20). Post-HIFU PSA nadir, 6-month PSA, PSA density, and early (<3wk) and late (6mo) MRI (T2-weighted, dynamic contrast-enhanced±diffusion-weighted) was assessed for predictive accuracy of cancer on postoperative biopsy, using receiver operating characteristic (ROC) analysis and sensitivity, specificity, and positive and negative predictive estimates. ROC areas for MRI and PSA were compared. Calculations for statistical significance (P≤0.05) were obtained in a subset of patients comparing area under ROC for 6-month MRI and PSA criteria, across 4 different histological definitions of disease significance.

RESULTS

Of 118 men, 111 underwent at least 1 postoperative biopsy (median 6 cores), with an overall positive biopsy rate of 37% (41/118), over a mean follow-up period of 716 days post-HIFU. Areas under ROC for early and late MRI were (depending on definition of significant disease) 0.65 to 0.76 and 0.77 to 0.85, respectively, with sensitivity, specificity, and negative predictive values of 68% to 91%, 52% to 55%, and 85% to 98% (early MRI), and 63% to 80%, 67% to 73%, and 86% to 97% (late MRI). The area under the ROC curve was statistically significantly higher for late MRI than 6 months and nadir PSA for residual disease >3mm or any Gleason 4 tumor.

CONCLUSIONS

Early and late MRI performed better than PSA measurements in the detection of residual tumor after focal therapy.

Nanoparticle-Enabled Selective Destruction of Prostate Tumor Using MRI-Guided Focal Photothermal Therapy

BACKGROUND

The Magnetic Resonance Imaging (MRI)-guided focal laser therapy has shown early promise in Phase 1 trial treating low/intermediate-risk localized prostate cancer (PCa), but the lack of tumor selectivity and low efficiency of heat generation remain as drawbacks of agent-free laser therapy. Intrinsic multifunctional porphyrin-nanoparticles (porphysomes) have been exploited to treat localized PCa by MRI-guided focal photothermal therapy (PTT) with significantly improved efficiency and tumor selectivity over prior methods of PTT, providing an effective and safe alternative to active surveillance or radical therapy.

METHODS

The tumor accumulation of porphysomes chelated with copper-64 was determined and compared with the clinic standard (18) F-FDG in an orthotropic PCa mouse model by positron emission tomography (PET) imaging, providing quantitative assessment for PTT dosimetry. The PTT was conducted with MRI-guided light delivery and monitored by MR thermometry, mimicking the clinical protocol. The efficacy of treatment and adverse effects to surround tissues were evaluated by histology analysis and tumor growth in survival study via MRI.

RESULTS

Porphysomes showed superior tumor-to-prostate selectivity over (18) F-FDG (6:1 vs. 0.36:1). MR thermometry detected tumor temperature increased to ≥55°C within 2 min (671 nm at 500 mW), but minimal increase in surrounding tissues. Porphysome enabled effective PTT eradication of tumor without damaging adjacent organs in orthotropic PCa mouse model.

CONCLUSIONS

Porphysome-enabled MRI-guided focal PTT could be an effective and safe approach to treat PCa at low risk of progression, thus addressing the significant unmet clinical needs and benefiting an ever-growing number of patients who may be over-treated and risk unnecessary side effects from radical therapies. Prostate 76:1169-1181, 2016. © 2016 Wiley Periodicals, Inc.

Emerging Technologies and Techniques in Radiation Therapy

The past decade has brought an improved ability to precisely target and deliver radiation as well as other focal prostate-directed therapy. Stereotactic body radiotherapy (SBRT), proton beam radiation, high-dose-rate (HDR) brachytherapy, as well as nonradiotherapy treatments such as cryoablation and high-intensity focused ultrasound are several therapeutic modalities that have been investigated for the treatment of prostate cancer in an attempt to reduce toxicity while improving cancer control. However, high-risk prostate cancer requires a comprehensive treatment of the prostate as well as areas at risk for cancer spread. Therefore, most new radiation treatment (SBRT, HDR, and proton beam radiation) modalities have been largely investigated in combination with regional radiation therapy. Though the evidence is evolving, the use of SBRT, HDR, and proton beam radiation is promising. Nonradiation focal therapy has been proposed mainly for partial gland treatment in men with low-risk disease, and its use in high-risk prostate cancer patients remains experimental.

Final Results of a Phase I/II Multicenter Trial of WST11 Vascular Targeted Photodynamic Therapy for Hemi-Ablation of the Prostate in Men with Unilateral Low Risk Prostate Cancer Performed in the United States

PURPOSE

Vascular targeted photodynamic therapy with WST11 (TOOKAD® Soluble) is a form of tissue ablation that may be used therapeutically for localized prostate cancer. To study dosing parameters and associated treatment effects we performed a prospective, multicenter, phase I/II trial of WST11 vascular targeted photodynamic therapy of prostate cancer.

MATERIALS AND METHODS

A total of 30 men with unilateral, low volume, Gleason 3 + 3 prostate cancer were enrolled at 5 centers after local institutional review board approval. Light energy, fiber number and WST11 dose were escalated to identify optimal dosing parameters for vascular targeted photodynamic therapy hemi-ablation. Men were treated with photodynamic therapy and evaluated by posttreatment magnetic resonance imaging and biopsy. Prostate specific antigen, light dose index (defined as fiber length/desired treatment volume), toxicity and quality of life parameters were recorded.

RESULTS

After dose escalation 21 men received optimized dosing of 4 mg/kg WST11 at 200 J energy. On posttreatment biopsy residual prostate cancer was found in the treated lobe in 10 men, the untreated lobe in 4 and both lobes in 1. At a light dose index of 1 or greater with optimal dosing in 15 men 73.3% had a negative biopsy in the treated lobe. Six men undergoing retreatment with the optimal dose and a light dose index of 1 or greater had a negative posttreatment biopsy. Minimal effects were observed on urinary and sexual function, and overall quality of life.

CONCLUSIONS

Hemi-ablation of the prostate with WST11 vascular targeted photodynamic therapy was well tolerated and resulted in a negative biopsy in the treated lobe in the majority of men. Dosing parameters and the light dose index appear related to tissue response as determined by magnetic resonance imaging and biopsy. These parameters may serve as the basis for further prospective studies.

Pilot Study to Assess Safety and Clinical Outcomes of Irreversible Electroporation for Partial Gland Ablation in Men with Prostate Cancer

PURPOSE

Partial prostate gland ablation is a strategy to manage localized prostate cancer. Irreversible electroporation can ablate localized soft tissues. We describe 30 and 90-day complications and intermediate term functional outcomes in men undergoing prostate gland ablation using irreversible electroporation.

MATERIALS AND METHODS

We reviewed the charts of 25 patients with prostate cancer who underwent prostate gland ablation using irreversible electroporation as a primary procedure and who were followed for at least 6 months.

RESULTS

Median followup was 10.9 months. Grade 3 complications occurred in 2 patients including epididymitis (1) and urinary tract infection (1). Fourteen patients experienced grade 2 or lower complications, mainly transient urinary symptoms, hematuria and urinary tract infections. Of 25 patients 4 (16%) had cancer in the zone of ablation on routine followup biopsy at 6 months. Of those with normal urinary function at baseline 88% and 94% reported normal urinary function at 6 and 12 months after prostate gland ablation, respectively. By 12 months only 1 patient with normal erectile function at baseline reported new difficulty with potency and only 2 patients (8%) required a pad for urinary incontinence.

CONCLUSIONS

Prostate gland ablation with irreversible electroporation is feasible and safe in selected men with localized prostate cancer. Intermediate term urinary and erectile function outcomes appear reasonable. Irreversible electroporation is effective in the ablation of tumor bearing prostate tissue as a majority of men had no evidence of residual cancer on biopsy 6 months after prostate gland ablation.

Comparison of ablation defect on MR imaging with computer simulation estimated treatment zone following irreversible electroporation of patient prostate

To determine whether patient specific numerical simulations of irreversible electroporation (IRE) of the prostate correlates with the treatment effect seen on follow-up MR imaging. Computer models were created using intra-operative US images, post-treatment follow-up MR images and clinical data from six patients receiving IRE. Isoelectric contours drawn using simulation results were compared with MR imaging to estimate the energy threshold separating treated and untreated tissue. Simulation estimates of injury to the neurovascular bundle and rectum were compared with clinical follow-up and patient reported outcomes. At the electric field strength of 700 V/cm, simulation estimated electric field distribution was not different from the ablation defect seen on follow-up MR imaging (p = 0.43). Simulation predicted cross sectional area of treatment (mean 532.33 ± 142.32 mm(2)) corresponded well with the treatment zone seen on MR imaging (mean 540.16 ± 237.13 mm(2)). Simulation results did not suggest injury to the rectum or neurovascular bundle, matching clinical follow-up at 3 months. Computer simulation estimated zone of irreversible electroporation in the prostate at 700 V/cm was comparable to measurements made on follow-up MR imaging. Numerical simulation may aid treatment planning for irreversible electroporation of the prostate in patients.

Dosimetric benefits of hemigland stereotactic body radiotherapy for prostate cancer: implications for focal therapy

OBJECTIVE

Compared with standard, whole-gland (WG) therapies for prostate cancer, focal approaches may provide equivalent oncologic outcomes with fewer adverse effects. The purpose of this study was to compare organ-at-risk (OAR) dosimetry between hemigland (HG) and WG stereotactic body radiotherapy (SBRT) plans.

METHODS

Volumetric-modulated arc radiotherapy-based SBRT plans were designed to treat the left HG, right HG and WG in eight patients, using five fractions of 8 Gy. OARs of interest included the contralateral HG, rectum, urinary bladder, urethra, penile bulb and contralateral neurovascular bundle.

RESULTS

Rectal V80% (the percentage of a normal structure receiving a dose of 80%) and V90% were significantly lower with HG plans than with WG plans (median values of 4.4 vs 2.5 cm(3) and 2.1 vs 1.1 cm(3), respectively, p < 0.05 by Student's t-test). Bladder V50% was also reduced significantly in HG plans (32.3 vs 17.4 cm(3), p < 0.05), with a trend towards reduction of V100% (3.4 vs 1.3 cm(3), p = 0.09). Urethral maximum dose and mean doses to the penile bulb and contralateral neurovascular bundle were also reduced significantly (42.0 vs 39.7 Gy, p < 0.00001; 13.3 vs 9.2 Gy, p < 0.05; and 40.2 vs 19.3 Gy, p < 0.00001, respectively).

CONCLUSION

Targeting an HG volume rather than a WG volume when delivering SBRT can offer statistically significant reductions for all OARs. Given the large magnitude of the reduction in dose to these OARs, it is anticipated that HG SBRT could offer a superior toxicity profile when compared with WG SBRT. This is likely to be most relevant in the context of salvaging a local failure after radiation therapy.

ADVANCES IN KNOWLEDGE

The dosimetric feasibility of HG SBRT is demonstrated. When compared with WG SBRT plans, the HG plans demonstrate statistically significant and large magnitude reduction in doses to the rectum, bladder, urethra, penile bulb and contralateral neurovascular bundle, suggesting the possibility of improved toxicity outcomes with HG SBRT. This is likely to be most relevant in the context of salvaging a local failure after radiation therapy.

Prostate Cancer Volume Estimation by Combining Magnetic Resonance Imaging and Targeted Biopsy Proven Cancer Core Length: Correlation with Cancer Volume

PURPOSE

Multiparametric magnetic resonance imaging often underestimates or overestimates pathological cancer volume. We developed what is to our knowledge a novel method to estimate prostate cancer volume using magnetic resonance/ultrasound fusion, biopsy proven cancer core length.

MATERIALS AND METHODS

We retrospectively analyzed the records of 81 consecutive patients with magnetic resonance/ultrasound fusion, targeted biopsy proven, clinically localized prostate cancer who underwent subsequent radical prostatectomy. As 7 patients each had 2 visible lesions on magnetic resonance imaging, 88 lesions were analyzed. The dimensions and estimated volume of visible lesions were calculated using apparent diffusion coefficient maps. The modified formula to estimate cancer volume was defined as the formula of vertical stretching in the anteroposterior dimension of the magnetic resonance based 3-dimensional model, in which the imaging estimated lesion anteroposterior dimension was replaced by magnetic resonance/ultrasound targeted, biopsy proven cancer core length. Agreement of pathological cancer volume with magnetic resonance estimated volume or the novel modified volume was assessed using a Bland-Altman plot.

RESULTS

Magnetic resonance/ultrasound fusion, biopsy proven cancer core length was a stronger predictor of the actual pathological cancer anteroposterior dimension than magnetic resonance estimated lesion anteroposterior dimension (r = 0.824 vs 0.607, each p <0.001). Magnetic resonance/ultrasound targeted, biopsy proven cancer core length correlated with pathological cancer volume (r = 0.773, p <0.001). The modified formula to estimate cancer volume demonstrated a stronger correlation with pathological cancer volume than with magnetic resonance estimated volume (r = 0.824 vs 0.724, each p <0.001). Agreement of modified volume with pathological cancer volume was improved over that of magnetic resonance estimated volume on Bland-Altman plot analysis. Predictability was more enhanced in the subset of lesions with a volume of 2 ml or less (ie if spherical, the lesion was approximately 16 mm in diameter).

CONCLUSIONS

Combining magnetic resonance estimated cancer volume with magnetic resonance/ultrasound fusion, biopsy proven cancer core length improved cancer volume predictability.

Focal cryotherapy of localized prostate cancer: a systematic review of the literature

Radical/whole gland treatment for prostate cancer has significant side-effects. Therefore focal treatments such as cryotherapy have been used to treat localized lesions whilst aiming to provide adequate cancer control with minimal side-effects. We performed a systematic review of Pubmed/Medline and Cochrane databases' to yield 9 papers for primary focal prostate cryotherapy and 2 papers for focal salvage treatment (radio-recurrent). The results of 1582 primary patients showed biochemical disease-free survival between 71-93% at 9-70 months follow-up. Incontinence rates were 0-3.6% and ED 0-42%. Recto-urethral fistula occurred in only 2 patients. Salvage focal cryotherapy had biochemical disease-free survival of 50-68% at 3 years. ED occurred in 60-71%. Focal cryotherapy appears to be an effective treatment for primary localized prostate cancer and compares favorably to radical/whole gland treatments in medium-term oncological outcomes and side-effects. Although more studies are needed it is also effective for radio-recurrent cancer with a low complications rates.

Phase I/II prospective trial of cancer-specific imaging using ultrasound spectrum analysis tissue-type imaging to guide dose-painting prostate brachytherapy

PURPOSE

To assess the technical feasibility, toxicity, dosimetry, and preliminary efficacy of dose-painting brachytherapy guided by ultrasound spectrum analysis tissue-type imaging (TTI) in low-risk, localized prostate cancer.

METHODS AND MATERIALS

Fourteen men with prostate cancer who were candidates for brachytherapy as sole treatment were prospectively enrolled. Treatment planning goal was to escalate the tumor dose to 200% with a modest de-escalation of dose to remaining prostate compared with our standard. Primary end points included technical feasibility of TTI-guided brachytherapy and equivalent or better toxicity compared with standard brachytherapy. Secondary end points included dose escalation to tumor regions and de-escalated dose to nontumor regions on the preimplant plan, negative prostate biopsy at 2 years, and freedom from biochemical failure.

RESULTS

Thirteen of fourteen men successfully completed the TTI-guided brachytherapy procedure for a feasibility rate of 93%. A software malfunction resulted in switching one patient from TTI-guided to standard brachytherapy. An average of 2.7 foci per patient was demonstrated and treated with an escalated dose. Dosimetric goals on preplan were achieved. One patient expired from unrelated causes 65 days after brachytherapy. Toxicity was at least as low as standard brachytherapy. Two-year prostate biopsies were obtained from six men; five (83%) were definitively negative, one showed evidence of disease with treatment effect, and none were positive. No patients experienced biochemical recurrence after a median followup of 31.5 (24-52) months.

CONCLUSIONS

We have demonstrated that TTI-guided dose-painting prostate brachytherapy is technically feasible and results in clinical outcomes that are encouraging in terms of low toxicity and successful biochemical disease control.

Comparison of Outcomes Between Preoperatively Potent Men Treated with Focal Versus Whole Gland Cryotherapy in a Matched Population

BACKGROUND AND PURPOSE

The refinement in the localization of prostate cancer tumor foci through transperineal template-mapping biopsies and MRI has led to an increased interest in lesion-directed focal prostatic cryoablation. Data are lacking, however, that compare the outcomes of whole-gland (WG) to focal ablation therapy (FT). The aim of our study was to assess both oncologic and functional outcomes between WG and FT cryoablation of the prostate after having matched patients for preoperative characteristics.

PATIENTS AND METHODS

We matched with a 1:1 ratio 317 men who underwent FT with 317 who underwent WG treatment in the Cryo Online Data (COLD) registry between 2007 and 2013. All patients were low-risk according to the D'Amico risk groups and were matched according to age at surgery. We only included preoperatively potent men. Oncologic outcomes were biochemical recurrence (BCR) free-survival defined according to the American Society for Radiation Oncology (ASTRO) and Phoenix criteria and assessed by Kaplan-Meier curves. Only patients with prostate-specific antigen (PSA) nadir data were included in oncologic outcome analysis. Functional outcomes were assessed at 6, 12, and 24 months after the procedure for erectile function (defined as ability to have intercourse with or without erectile aids), urinary continence, urinary retention, and rates of fistula formation.

RESULTS

Median age at the time of the procedure was 66.5 years (standard deviation [SD] 6.6 y), and median follow-up time was 58.3 months. After surgery, 30% (n=95) and 17% (n=55) of the men who received WG and FT, respectively, underwent biopsy, with positive biopsy rates of 11.6% and 14.5%, respectively. BCR-free survival rates at 60 months according to the Phoenix definition were 80.1% and 71.3% in the WG and FT cohorts, respectively, with a hazard ratio of 0.827; according to the ASTRO definition, they were 82.1% and 73%, respectively (all P ≥ 0.1). Erectile function data at 24 months was available for 172 WG and 160 FT treated men. Recovery of erection was achieved in 46.8% and 68.8% of patients in the WG and FT cohorts, respectively (P=0.001). Urinary function data at 24 months was available for 307 WG and 313 FT patients. Continence rates were 98.7% and 100% for WG and FT groups, respectively (P=0.02). Urinary retention at 6, 12, and 24 months was reported in 7.3%, 1.9%, and 0.6%, respectively, in the WG arm, and in 5%, 1.3%, and 0.9%, respectively, in the FT arm. Finally, only one fistula was reported in each group.

CONCLUSIONS

Men with low-risk prostate cancer who underwent FT cryoablation had comparable BCR-survival rates at 60 months to patients treated with WG. However, FT patients had higher erectile function preservation rates at 24 months post-procedure. Urinary continence, retention and fistula rates were similar between the two treatment groups.